1. Field of the Invention
The present invention relates to a character recognition device that recognizes a character-writing operations performed by its housing including an acceleration sensor while being moved in a spatial plane, based on measurement results from the acceleration sensor, and a recording medium.
2. Description of the Related Art
Conventionally, numerous technologies have been proposed as a technology to measure a person's character-writing operation with an inertial sensor, and measurement results are loaded into a computer. For example, in Japanese Patent Application Laid-Open (Kokai) Publication No. 2009-099041, a technology is proposed in which an acceleration sensor is housed in a pen-tip, and measurement results of this acceleration sensor are extracted as the movement trajectory of the pen-tip. Additionally, in Japanese Patent Application Laid-Open (Kokai) Publication No. 2008-070920, a technology is proposed in which a mobile phone device includes an acceleration sensor, and input information specified by a handwriting operation is recognized based on movement information of the device body corresponding to a detection result of the acceleration sensor.
However, most of the technologies, which use an acceleration sensor to perform character recognition, have a problem in that they calculate speed from acceleration by integrating a measurement result of the acceleration sensor two times, and use the movement trajectory of this position calculated from speed of character recognition. In methods such as these, problems regarding failures to detect the integration initial state (start writing position), and integration errors occur. Additionally, it is necessary to integrate the output of an angular velocity sensor to track changes of gravitational direction in order to eliminate the strong disturbance of gravity from measurement data. Since the above-described problem regarding failures to detect the integration initial state and integration errors exist, it is extremely difficult to realize reliable character recognition.